1. RUBY
:
The Wheel Technology

2. HISTORY
Ruby was conceived on February 24, 1993
by Yukihiro Matsumoto (a.k.a “Matz”)who wished to
create a new language that balanced function
programming with imperative programming.
Matsumoto has stated, "I wanted a scripting language
that was more powerful than Perl, and more object-
oriented than Python.
At a Google Tech Talk in 2008 Matsumoto further
stated, "I hope to see Ruby help every programmer in
the world to be productive, and to enjoy
programming, and to be happy. That is the primary
purpose of Ruby language."

3. PRINCIPLE
Ruby is said to follow the principle of least
astonishment (POLA), meaning that the language
should behave in such a way as to minimize
confusion for experienced users.
Matsumoto has said his primary design goal was to
make a language which he himself enjoyed
using, by minimizing programmer work and
possible confusion.

4. COMPARISON
Dynamic vs. Static typing
Scripting vs. Complied Language
-use interpreter -use compiler
Object oriented vs. Procedure oriented

5. WHAT IS RUBY ?
Paradigm : Multi-paradigm
1.object-oriented
2. functional,
3.dynamic
4. imperative
Typing- : : 1.Dynamic
discipline 2.Duck
3.strong
Non commercial : Open Source
Influenced by : Ada, C++, Perl, Smalltalk,
Python , Eiffel

6. CONT..
Os : cross platform(windows , mac os , linux etc.)
Stable release : 1.9.2 (February ,18 2011)
Major implementations : RubyMRI , YARV , Jruby
, Rubinius, IronRuby , MacRuby , HotRuby
License : Ruby license or General public license
Usual file extension : .rb , .rbw
Automatic memory management(Garbage collection)

7. WHY RUBY?
Easy to learn
Open source (very liberal license)
Rich libraries
Very easy to extend
Truly Object-Oriented
-Everything is an object.
Single inheritance
- Mixins give you the power of multiple inheritance
with the problems .

8. SIMPLE “ HELLO, WORLD ” PROGRAM
# simply give hello world Comment in ruby
puts “hello , world..”
Output:
hello , world..

9. WHERE TO WRITE RUBY CODE?
IDE or Editors:
1. Net beans
2. Eclipse(mostly used today)
3. Text Mate (mac os)
4. Ultra editor
5. E
6. Heroku( completely online solution for application )

10. RUBY SYNTAX
Ruby syntax is similar with Perl and Python .
1.Adding comment
- All text in ruby using # symbol consider as
comment.so that ruby interpreter ignored it.
1.a For large block
=begin
This is a multi-line block of comments in a Ruby
source file.
Added: January 1, 2011
=end
Puts “This is Ruby code

11. CONT..
2.Using parentheses :
- parentheses are optional in ruby
Ex.
In below ,you could call it like this..
movie.set_title(“Star Wars”)
Or you could call it without parentheses
movie.set_title “Star Wars”
Require, when chaining methods are used,
Ex.
puts movie.set_title(“Star Wars”)

12. CONT..
3.Using semicolons
Semicolons are a common indicator of a line or
statement ending. In Ruby, the use of semicolons
to end your lines is not required.
def add_super_power(power)
@powers.add(power)
end
The only time using semicolons is required is if you
want to use more than one statement on a single
line
def add_super_power(power)
@powers.add(power); puts “added new power”
end Indicate more than one
statement on single line

13. KEYWORDS & IDENTIFIERS
BEGIN END alias and Begin
break case def class defined?
do else elsif end ensure
false for if in module
next nil not or redo
rescue retry undef self super
then true return unless until
when while yield

14. VARIABLES
Local variables:begin with lowercase or underscore
Ex : alpha , _ident
Pseudovariables : self ,nil
Global variables: begin with $ (dollar sign)
Ex: $beta, $NOT_CONST
Instance variables: begin with @ sign
Ex:@foobar
Class variables: begin with @@sign
Ex:@@my_var
Constants : begin with capital
Ex:Length

15. OPERATORS
:: Scope
[] Indexing
** Exponentiation
+-!~ Unary
*/ +-% Binary
<< >> Logical shifts
&(and) |(or) ^(xor) Bitwise
< >= < <= Comparision
&& || Boolean and ,or
.. … Range
?: Ternary decision

16. LOOPING AND BRANCHING
“ If ” Form “ Unless ” Form
if x<5 then unless x>=5 then
state1 state1
end end
if x<5 then unless x>=5 then
state1 state1
else else
state2 state2
end end
x = if a>0 then b else c end x = unless a<=0 then b else
c end

17. LOOPING (FOR, WHILE, LOOP )
1. # loop1 (while)
i=0
while i < 10 do
print “ # {i} ” output: 0 to 9
i+=1
end
2. # loop2(loop)
i=0
output: 0 to 9
loop do
print “ # {i} ”
i+=1
break if i>10
end

18. CONT..
3.# loop3 (for)
for
i in 0..9 do output: 0 to 9
print “#{i}”
end

19. STANDARD TYPE
- Integer within a certain range .
(normally -230 to 230-1 or -262 to 262-1)
Interger
Bignum Fixnum
-Also support Float numbers
- Complex numbers

20. CONT..
 123456 # Fixnum
 123_456 # Fixnum (underscore ignored)
 -543 # Negative Fixnum
 123_456_789_123_345_789 # Bignum
 0xaabb # Hexadecimal
 0377 # Octal
 0b101_010 # Binary

21. CONT..
Some of operation on numbers:
a= 64**2 # ans.4096
b=64**0.5 # ans. 8.0
c=64**0 # ans.1
Complex number
a=3.im #3i
b= 5-2im #5-2i
c=Complex(3,2) # 3+2i
Base conversion
237.to_s(2) #”11101101”
237.to_s(8) #”355 ”
237.to_s(16) #”0xed ”

22. OOP IN RUBY
In ruby , every thing is an object . like, string, array,
regular expression etc.
Ex.
- “abc”. upcase # “ABC”
- 123.class #Fixnum
- “abc”.class #String
- “abc”.class .class #Class
- 1.size # 4
- 2.even? # true
- 1.next # 2

23. STRINGS
Ruby strings are simply sequences of 8-bit bytes.
They normally hold printable characters, but that is
not a requirement; a string can also hold binary data.
Strings are objects of class String.
Working with String:
1.Searching
str =“Albert Einstein ”
p1= str.index(?E) #7
p2= str.index(“bert”) #2
p3=str.index(?w) #nil

24. CONT..
1.a Substring is present or not?
str =“mathematics”
flag1=str.include? ?e # true
flag2=str.include? “math” # true
2. Converting string to numbers
x=“123”.to_i #123
y=“3.142”.to_f #3.14
z=Interger(“0b111”) #binary –return 7

25. CONT..
3. Counting character in string
s1=“abracadabra”
a=s1.count(“c”) #1
b=s1.count(“ bdr ”) #5
4. Reversing a String
s1=“Star World”
s2=s1.reverse # “dlroW ratS”
s3=s1.split(“ ” ) # [“Star” ”World”]
s4=s3.join(“ ”) # “Star World ”

26. CONT..
5. Removing Duplicate characters
s1=“bookkeeper”
s2=s1.squeeze # “ bokeper ”
s3=“Hello..” # specific character only
s4=s3.squeeze(“.”) # “hello.”

27. ARRAY & HASHES
The array is the most common collection class and
is also one of the most often used classes in Ruby.
An array stores an ordered list of indexed values
with the index starting at 0.
Ruby implements arrays using the Array class.
Creating and initializing an array
Ex. a=Array[1,2,3,4] or
a=[1,2,3,4] or
a=Array.new(3) #[nil,nil,nil]

28. CONT..
Finding array size
x=[“a”, “b”, “ c”]
a=x.length #3
or
a=x.size #3
Sorting array
a=[1, 2 , “three ”, “four”,5,6]
b=a.sort {|x,y|x.to_d<=>y.to_s }
# ans. [1,2,5,6, “four”, “three”]
x=[5,6,1,9]
y=x.sort{|a,b| a<=>b}
#ans.[1,5,6,9]

29. HASHES
 Hashes are known as in some circle as associative
arrays , dictionaries.
Major difference between array & hashes
- An Array is an ordered data structure.
- Whereas a Hash is disordered data structure.

30. CONT..
Hashes are used as “key->value” pairs
Both key & value are objects.
Ex.
h=Hash{ “dog”=> “animal” , “parrot”=> „”bird” }
puts h.length #2
h[„dog‟] #animal
h.has_value? “bird” # true
h.key? “ cat” #false
a=h.sort #[[“dog”, “animal”],[“parrot”, “bird”]]
# It convet into array

31. REFERENCE
Books :
1. programming ruby language
-Yukihiro Matsumoto
2.programming ruby language
-David black
3.The Pragmatic Programmer's Guide
- Yukihiro Matsumoto
4. The Ruby Way
-Hal Fulton
5. The ruby -In Nutshell
- Yukihiro Matsumoto
Sites:
http://www.ruby-lan.org

32. THANK YOU

33. PREVIOUS SESSION
History
Principle
What is Ruby?
Keyword & Variable
Standard Type
Object
Looping &Branching
Array
String
Hashes

34. THIS SESSION
Module
Method in Ruby
Class Variable & Class Method
Inheritance
Method Overriding
Method Overloading

35. CONT..
Ruby On Rails -Web Development
What is Rails?
Rails Strength
Rails & MVC Pattern
Rails Directory Structure
Creating Simple Web application

36. METHOD IN RUBY
How to define method in class?
module pqr
class xyz
def a
end
….
end
end
Example:
class Raser
def initialize(name,vehicle) # constructor of class
@name=name
@vehicle=vehicle
end
end

37. CONT..
racer=Racer.new(“abc”, “ferrari ”)
creating object racer of class
Racer
puts racer.name # give abc
puts racer.vehicle # give ferrari
puts racer.inspect #give abc & ferrari both

38. INHERITANCE
Inheritance is represented in ruby
subclass<superclass
(extends keyword in java replace by < in ruby)
Example:
class Racercomp<Racer
def initialize (name,vehicle,rank)
super(name,vehicle)
@rank=rank
end
end
x=Racercomp.new(“xyz”, “ferrari”, “10”)
puts x.inspect

39. METHOD OVERRIDING
 class xyz
def name
puts “hi ,i am in xyz…”
end
end
class abc<xyz
def name
puts “hi, i am in abc…”
end
end
a=xyz.new
b=abc.new
puts a.name # hi, i am in xyz
puts b.name # hi, i am in abc

40. METHOD OVERLOADING
class xyz
def hello(name1)
puts “hello ,#{name1}”
end
def hello(name1,name2)
puts “hello ,#{name1} #{name2}”
end
a=xyz.new
puts a.hello(i am) # hello , i am
b=xyz.new
puts b.hello(i am,fine) # hello , i am fine

41. ATTR_READER
Ruby provide methods using attr_reader
class Song
attr_reader :name, :artist, :duration
end
a=Song.new( “p” , “q”, “r”)
puts a.inspect

42. Ruby on Rails -
Web Development

43. WHAT IS RAILS?
An Extremely Productive web application
framework that is written in Ruby by David Hansson.
Fully stack Framework
- Includes everything needed to create database
drive Web application using MVC pattern.
- Being a full stack Framework means that all
layer are built to work seamlessly together.

44. RAILS & MVC PATTERN
 M - Model(Active Record)
 V – View(Active View)
 C – Controller(Active Controller)

45. CONT..

46. MODEL- ACTIVE RECORD
Provide access to Database table
- Record CRUD(Create, Read, Update , Delete)
It define also Validation & Association

47. VIEW – ACTIVE VIEW
The user screen or Web page of your application.
It should not contain any logic.
It should not know about model.
View are similar to PHP or ASP page.
It contain little presentation logic whenever possible.
denoted with .rhtml extension.

48. CONTROLLER –ACTIVE CONTROLLER
The purpose of controller
- Only flow control.
- Handle user request.
- Retrieve Data from model.
- Invoke method on model.
- Send to view and respond to users.

49. RAILS DIRECTORY STRUCTURE

50. SIMPLE APPLICATION
type rails name of
application in plural

51. CONT..
http://localhost:
3000

52. CONT..

53. CONT..

54. REFERENCE
Books :
1. Head first rails
- David Griffiths
2. Begging of rails
- Steven Holzner
3.The Pragmatic Programmer's Guide
- Yukihiro Matsumoto
4. The Ruby Way
- Hal Fulton
5. Agile web development –Ruby on Rails
- David Heine Meier Hansson
Sites:
http://www.ruby-lan.org

55. THANK YOU